起泡剂对硫化矿浮选的影响

研究了起泡剂MIBC、BK201、松醇油及2-乙基己醇对石英及黄铁矿单矿物浮选行为的影响, 并进行了实际矿石浮选试验。单矿物试验结果表明: 石英通过泡沫夹带进入浮选精矿, 而黄铁矿通过疏水上浮和泡沫夹带的双重作用进入浮选精矿。不同起泡剂作用下, 精矿中泡沫水回收率越高, 石英和黄铁矿的浮选回收率越高, 不同起泡剂对石英和黄铁矿具有不同的夹带效果, 使石英和黄铁矿浮选回收率最高的起泡剂分别为BK201和MIBC。实际矿石浮选试验表明: 浮选产率、精矿品位及回收率与泡沫水回收率密切相关, 泡沫水回收率增大, 精矿产率增大, 而品位降低。选择合适的起泡剂能够增加硫化矿物的回收率并降低石英的回收率, 获得较好的浮选分离效果。     

Flotation frother mixtures: Decoupling the sub-processes of froth stability,froth recovery and entrainment

The flotation process consists of two distinct phases: the pulp and froth phase. One of the main roles of the froth phase is to create a suitable environment for the separation of floatable, valuable minerals from non-selectively recovered, entrained gangue minerals. As a result the froth phase plays a significant role in the metallurgical performance of industrial flotation cells. Froth stability is important for the recovery of valuable minerals. However, a stable froth may contribute to increased entrainment and, consequently, a lower grade.This study compares the effect of frother mixtures with that of their single component frothers on the froth stability, froth recovery and entrainment of a platinum-bearing UG2 ore using polyglycol and alcohol frothers. The study showed that frother mixtures resulted in a greater froth stability than either of their component frothers. The increased froth stability was reflected in increased froth recoveries and greater overall recoveries. However, the important aspect in the use of frother blends was that they altered the froth structure and resulted in a lower degree of entrainment. This, together with the increased recovery, resulted in higher grades of valuable mineral recovered to the concentrate when using the frother mixtures.     

The effect of frother blends on the flotation performance of selected PGM bearing ores

Concentrators processing PGM bearing ores make use of polysaccharide depressants to reduce the recovery of the undesired naturally floatable gangue minerals, mainly silicates, present in the ore. Recent work has shown that high depressant dosages can completely depress naturally floatable gangue and thus prevent it from reporting to the concentrate. These high depressant dosages can, however, have a negative effect on the recovery of valuable minerals present in the ore by reducing the stability of the froth. In order to counterbalance the effects of depressant addition, frothers are added. It is, however, preferable to maintain independent control over bubble size and froth stability which is difficult to achieve with only one frother. An alternative strategy is to use a blend of frothers, e.g. a weaker frother in combination with a stronger frother. Such a system allows an additional degree of freedom: changing the ratio of the two frothers provides more independent control of bubble size and froth stability. This study demonstrates through the use of batch flotation tests how blending low molecular weight alcohols with commercially available frothers impacts the solids and water recovery, as well as the valuable mineral recovery and concentrate grade in different PGM ores. Higher water and solids recoveries together with higher valuable mineral recoveries (>90% copper and >70% nickel) were obtained from tests using frother blends.     

浮选起泡剂及其研究新进展

概要分析了浮选起泡剂的基本结构及其对起泡性能的影响,从天然起泡剂、酸性起泡剂、碱性起泡剂、中性起泡剂5个方面对常规浮选起泡剂进行了较详细的介绍,总结了近年来新型浮选起泡剂的研究进展及组合起泡剂的应用情况,最后预测了浮选起泡剂今后的发展趋势。     

Frother function–structure relationship: Dependence of CCC95 on HLB and the H-ratio

Although the number and diversity of commercial frothers has steadily increased to meet flotation industry demands, frother selection is still mainly empirical. As part of a general structure–property study, the paper presents a correlation between the critical coalescence concentration (CCC95) and H-ratio for surfactants used as flotation frothers. The CCC95 were determined in 0.8 m³ mechanical flotation cell. The H-ratio was a substitution of hydrophile-lipophile balance (HLB) and determined through high resolution proton nuclear magnetic resonance (¹H NMR) spectrometry. A large data set, consisting of 45 surfactants from four frother families, was used to develop the correlation. It is shown that the H-ratio can substitute for HLB. The potential of NMR both to identify the frother family and to derive the H-ratio in predicting CCC95 for commercial frothers is discussed.     

硫化矿浮选中相似结构的起泡剂的浮选特性研究

在浮选工艺条件及其它药剂条件相同的情况下,从铅锌矿物的硫化矿浮选回收的变化角度出发,考察两种相似化学结构的起泡剂聚丙二醇单甲基醚（DPM）和聚丙二醇单丁基醚（DPB）的浮选特性。通过分析在铅锌硫化矿的浮选试验结果中所表现的浮选速率的差异以及粗精矿各粒级的分布差异和有价金属量的分布差异,研究了起泡剂DPM和DPB浮选特性的差异。研究结果表明:起泡剂DPB的浮选效率优于DPM。起泡剂DPB对回收较细粒级的铅矿物更有利,而起泡剂DPM对回收较粗粒级的锌矿物更有利。起泡剂DPB比DPM更有利于提高铅锌精矿的品位。      

新型高效合成起泡剂替代2^#油的研究与实践

为了解决国内起泡剂品种单一、质量不稳定、货源紧张、价格上涨等诸多问题，研制了新型合成起泡剂ＢＫ－２０１。通过小型试验、工业生产实践证明，该药剂适应永平铜矿的矿石性质，具有起泡能力强、浮选速度快、适应性强、用量小、价格低等特点，它能完全取代现场生产所用的以松节油为原料的２＃油，在选别指标相当时，能降低起泡剂用量量４２％以上，矿山每年因降低药费可增加经济效益５３万元以上。     

Investigation of the interactive effects of the reagent suite in froth flotation of a Merensky ore

Interpretation of the behaviour of reagents in flotation is made complex by the existence of secondary effects, which can override the desired effects that enable effective separation, in addition to a predominant role of a flotation reagent, and the incomplete liberation of the mineral particles. Moreover, accumulation of dissolved ions due to the water recycle and reuse practice in processing circuits, which alters the chemical environment in the pulp and impacts the overall performance of the process, adds to this complexity. Therefore, it is often challenging to precisely assess individual contributions of the reagents to the overall performance, and hence the need for a holistic approach in evaluating the behaviour of reagents in flotation. Factorial design of experiments offers such an approach. This study used a factorial design approach in an effort to determine the interactive effects between chosen flotation reagents; collector, depressant, frother and water quality on the metallurgical performance of a Merensky ore. Increasing the ionic strength of the plant water increased recoveries, and the effect on decreasing concentrate grade was minimal, therefore the practice of water recycle and reuse should not impose any adverse impact during beneficiation of the PGM-bearing ore from the Merensky reef. It was also observed that higher recoveries were obtained with high ionic strength plant water than high frother dosage, indicating that the use of saline water in froth flotation of certain ores can replace the use of frothers, thus reducing costs. The factorial design approach can be useful in evaluating the simultaneous effects of such variables in the flotation process, thereby giving better understanding of their overall effect on the whole process.     

浮选气泡粒度分布规律

定量研究不同起泡剂的气泡粒度分布特性及其差异,选择仲辛醇、松油醇和MIBC等起泡剂,在XDF-2L实验室浮选机上利用图像分析法测定了不同类型起泡剂下气泡的粒度大小,研究了起泡剂类型和浓度对气泡粒度分布的影响。结果表明,浮选槽中不同起泡剂在不同浓度下的气泡粒度分布遵循upper-limit分布或对数正态分布规律;起泡剂种类和浓度均会影响气泡粒度分布;随起泡剂浓度的增加,小气泡所占比例迅速增多,大气泡明显减少,粒度范围变窄,当超过临界值时,气泡粒度分布基本不变;仲辛醇、松油醇和MIBC的临界兼并浓度分别为0.066,0.113和0.181 mmol/L;当起泡剂浓度大于临界兼并浓度时,仲辛醇和松油醇产生的气泡大小略低于MIBC。     

浮选柱选用适宜起泡剂的试验研究

气含率在旋流-静态微泡浮选柱分选过程中起到很重要的作用,而起泡剂是影响气含率的关键因素。通过对730系列起泡剂在浮选柱应用中的气含率研究以及结合云南大红山铜矿的选矿实践,比较5种起泡剂的性能指标,综合精矿品位和回收率得出730C更适配于旋流-静态微泡浮选柱。     

Towards a new process for the flotation of quartz

Results obtained from flotation experiments performed on three different quartz concentrates demonstrate that quartz can be floated in diluted solutions of hydrofluoric acid (HF) simply by the aid of frothers alone. The recovery was found to be highly dependent on the choice of frother and strongly positively correlated with the concentration of both frother and HF, as well as with the HF conditioning time. Experiments using HNO₃ instead of HF showed no flotation of quartz. Of the five different frothers tested, Brij 58 was found to produce the highest recovery. Good recoveries were also obtained for Dowfroth 400 and Flotanol C07, whereas Dowfroth 200 and MIBC failed to float any quartz. From experiments in which a given feed material were tested at two different particle size distributions it was found that highest recoveries were obtained for the finer feed. Chemical analysis of the floated products showed that these were significantly purer than their corresponding feed materials, and that most of the contaminating elements were concentrated in the sink fraction that remained in the cell. Contact angle measurements corresponded well with flotation recoveries.     

Frother analysis: Some plant experiences

A colorimetric technique, originally developed for methyl iso butyl carbinol (MIBC) based on the Komarowsky reaction, has been extended to a wide range of common mineral flotation frothers. The procedure, which is briefly described, is suited to on-site determination as shown in a series of industrial case studies. Some observations described include: distribution of frother down a bank and between pulp and froth; evidence of alcohol contaminants; and mass balancing. The ability to monitor frother will help interpret cell hydrodynamics and should help optimize the type, amount and location of frother addition.     

Frother persistence: A measure using gas holdup

Persistence here refers to the how long a frother remains effective in producing small bubbles, one of its prime functions in flotation. One way to evaluate is to track gas holdup over time while air is sparged into a column: if frother is depleted bubble size will start to increase consequently increasing bubble rise velocity and hence decreasing gas holdup. Persistence of nine frothers was evaluated in this manner. Polyglycol frothers exhibited high persistence with gas holdup virtually constant over 50 h compared with alcohol frothers. The alcohols divided into two groups, one showing steady decline in gas holdup, e.g., 1-hexanol, and a second group exhibiting a sharp decline at a given time, e.g., MIBC. Tests on MIBC showed increasing concentration extended persistence while increasing gas velocity and increasing bubble size decreased persistence. The decrease in gas holdup was related directly to measured decrease in frother concentration. It appears that the transport of frother to and through the froth and from froth to atmosphere needs to be considered.     

高效起泡剂的浮选特性及可生物降解性研究

为了满足环保的要求,高效起泡剂的选择既要考虑其对选矿指标的影响,也要考虑其对环境保护的影响。通过铅锌选矿试验对一种起泡剂BK212与常用的松醇油进行了浮选特性的对比研究,同时采用生物呼吸曲线法对两种起泡剂进行了可生物降解性对比研究。研究结果表明:起泡剂BK212不仅浮选速度快,药剂用量少,而且可生物降解性好,是一种高效绿色的起泡剂。      

Rougher flotation of copper sulphide ore using biosolids and humic acids

In the quest of new, less hazardous, and more ambient-friendly froth flotation reagents, the use of biosolids or humic acids as both collector and frother for the concentration of copper sulphide ores was investigated. Rougher flotation tests were conducted in Denver cells on a laboratory scale, and metallurgical indicators such as copper recovery, copper concentrate grade, and concentration and enrichment ratios were compared with those obtained under similar conditions but using conventional collectors and frothers for the industrial flotation of copper sulphide ores. With a dosage of 10% (w/w) biosolids, copper recovery and grade were 26% and 0.81%, respectively. The copper recovery and grade obtained with 1.5% (w/w) salt of humic acids were 29.7% and 3.5%, respectively. A significantly higher copper recovery (65.1%) was obtained with conventional industrial collectors and frothers, but the grade was also low (3.1% Cu). With the same dosage of humic substances, humic acid show that the flotation rate constant was significantly higher (0.2 min⁻¹) than that obtained with the same dosage of biosolids (0.09 min⁻¹). These results indicate that humic acids have more affinity than biosolids for copper-containing mineral species, and also show that biosolids and humic acids could be used as both collector and frother in the sulphide mineral concentration process by froth flotation. Because the distribution of iron in the concentrate obtained with biosolids is highest, these materials seem to have more affinity for pyrite.     

起泡剂对铜硫铁矿的浮选效果试验研究

针对冬瓜山铜硫铁矿的矿石性质,用几种不同起泡剂进行了优先浮铜、磁尾选硫的选矿试验,试验研究结果表明,MIBC(甲基异丁基甲醇)和丁基醚醇具有起泡性能好,泡沫层厚度高,用量少等特点,可取得较好的选矿指标,对于优先浮铜作业,使用丁基醚醇作起泡剂时选别效果最好,药剂成本最低;对于磁尾选硫作业,使用MIBC作起泡剂可取得较好的选矿指标,同时单位药剂成本最低。     

Frother-related research at McGill University

Over the past ten years the Mineral Processing group at McGill University has developed techniques to determine gas dispersion properties (gas superficial velocity, gas holdup, bubble size and bubble surface area flux) in flotation machines. This work is finding application in metallurgical diagnostics and cell characterization. The picture, however, will remain incomplete until the impact of chemistry on bubble production, and hence on gas dispersion, is understood. This has prompted investigations into frothers.There are two areas addressed in this communication: frother analysis and frother characterization.Coincident with the centenary, for 100 years there was no convenient frother analysis procedure. A colorimetric technique originally developed for alcohols had been applied to MIBC (Parkhomovski, V.L., Petrunyak, D.G., Paas, L., 1976. Determination of methylisobutylcarbinol in waste waters of concentration plants. Obogashchenie Rud 21 (2), 44–45). Using this as a starting point, the technique was successfully extended to a wide range of commercial frothers and shown to be robust against most common ‘contaminants’. The technique is readily used on-site and some observations from plant surveys are described.Characterization of frothers has taken two routes, determining water carrying rate and investigating properties of thin bubble films.Second only to transporting particles the recovery of water by bubbles has the most influence on metallurgy. The question posed was whether this ‘water carrying’ property could be related to frother type. In a specially designed column the volume rate of water to the overflow per unit cross-sectional area (‘carrying rate’, J_wo) and gas holdup (ε_g) at controlled froth depths were measured. The J_wo–ε_g relationship proved approximately linear and dependent on frother type, with four frother ‘families’ being identified.Bubble thin films have been studied for soaps and the techniques were adapted for frothers. From infrared analysis it became apparent that the frother molecule, while itself not seen, had an impact on organizing water molecules, apparently forming a film of bound water on the bubble surface. Exploiting the interference pattern generated in UV/Vis the film thickness (d) was determined; for MIBC d was less than 160 nm while for DF250 d was ∼600 nm. Taking a representative frother from the four families identified above, the water carrying rate at a given gas holdup increased with film thickness.Possible implications of the findings on the role of frother in bubble production are explored.     

Case studies on the performance and characterisation of the froth phase in industrial flotation circuits

This paper deals with two separate case studies investigating the froth phase performance and characterisation of two industrial rougher/scavenger flotation circuits. Froth phase performance was quantified using a mass balance approach to estimate froth zone recovery. Measured characteristics of the froth phase included frother solution concentration determined by gas chromatography, and the time taken for an equilibrium froth sample to decay to one-half of its original froth height. The latter measurement is referred to as the ‘froth half-life’ and is strongly linked to froth stability. Special methods and techniques developed to preserve frother in solution and to measure froth half-life are briefly described. The frother type in the first case study was a mixture of straight and branched alcohols, whilst the frother type in the second case study was a mixture of alcohols, aldehydes and triethoxybutane. The first case study focussed on a flotation circuit treating a low grade ore containing only a small fraction of floatable copper sulphide minerals, while the second case study focussed on a flotation circuit treating a higher grade complex sulphide ore containing significant quantities of chalcopyrite, galena, sphalerite and pyrite.It was found that froth zone recovery of valuable mineral generally decreased down-the-bank of the two industrial rougher/scavenger circuits. Moreover, decreases in froth zone recovery significantly limit the overall cell recovery of valuable mineral achievable from the plant scavenger cells. However, the decrease in froth zone recovery could not be linked to the removal of frother from the pulp solution to the concentrate product in the preceding rougher flotation stages. Measurements of residual frother in solution suggested that, approximately, only 5–10% of the added frother was removed into the rougher/scavenger concentrate, with the remainder appearing in the scavenger tailings. This finding suggested there was apparently adequate frother in solution in the scavenger stages.There was, however, a correlation to the froth half-life, with the froth half-life also generally decreasing down-the-bank. A simple, empirical model, based on the froth half-life and froth residence time of gas, is proposed here to predict froth zone recovery. Further, it is proposed that the froth stability, as measured by the froth half-life, is strongly linked to the presence of particles in the froth, with poorly mineralised scavenger froth characterised by a short half-life and, potentially, a low froth zone recovery. The importance of particles on froth stability was confirmed in separately conducted laboratory experiments. These experiments also demonstrated the wide variation in froth stability behaviour between different frother types.     

Frother structure–property relationship: Effect of alkyl chain length in alcohols and polyglycol ethers on bubble rise velocity

In mineral flotation, frothers are used to produce fine bubbles, reduce bubble rise velocity, and stabilize the froth, three properties that enhance the flotation process. These properties depend on the frother structure and this paper is part of an investigation into the frother structure-property relationship. The property here is bubble rise velocity and the structural variation is alkyl chain length of two frother families, alcohols and polyglycols. Single bubble rise velocity profiles were determined in a 350 cm column. Velocity at 300 cm as a function of concentration is determined and as a measure of the impact of structure on reduction in bubble rise velocity the concentration at minimum velocity (CMV) is estimated. The effect of increasing alkyl chain length is to decrease CMV by about ca. 90% in alcohols and ca. 70% in polyglycols for every one carbon addition. Taking log CMV as a function of the number of carbons in the alkyl chain gives a series of self-similar linear plots. An argument relating bubble rise velocity to surfactant molecule packing on the bubble surface is proposed.     

Effect of frothers and dodecylamine on bubble size and gas holdup in a downflow column

Bubble size and gas holdup were characterized in a two phase gas–water system in a laboratory downflow column. The effect of the cationic surfactant dodecyl amine (MW 185, HLB 10.7) and the frothers MIBC (MW 102, HLB 6.05) and polyglycol F507 (MW 425, HLB 8.63) on the bubble size and gas holdup were investigated. In addition, the effect of blends of MIBC-dodecyl amine (DDA) and F507-DDA on these parameters was assessed. The bubble Critical Coalescence Concentration (CCC) followed the order MIBC > DDA > F507. When blending the frothers with DDA at a concentration below its CCC, the frother CCC decreased and bubbles of finer size were obtained below and above the frother CCC. Static surface tension measurements of aqueous solutions with frothers and DDA as well as with frothers-DDA blends show coadsorption of DDA at the air/aqueous solution interface. The surface tension of aqueous solutions prepared with the blends decreased with the addition of DDA and varied linearly with the frother concentration within the concentration range studied. The gas holdup in the downflow column was determined by the bubble size and decreased with the bubble size. It is shown that frother-DDA blends gave the lowest gas holdup in the downflow column. This work is relevant for the reverse flotation of quartz from iron ores using amine collectors in cells with downflow systems.